1. Field of the Invention
The present invention generally relates to a development device, and a process cartridge and an image forming apparatus, such as a copier, a printer, a facsimile machine, or a multifunction machine having at least two of these capabilities, that includes a development device.
2. Description of the Related Art
Development devices that include a development roller having surface unevenness are known. For example, JP-2008-292594-A proposes forming projections having a substantially identical height and recesses having a substantially identical depth regularly in the surface of the development roller. Such configurations are advantageous in that toner present on the projections can be removed by a developer regulator (i.e., a doctor blade) and that the amount of toner carried on the development roller can be constant because only toner present inside the recesses can be carried thereon. The amount of toner carried to a development range can be set to a desired amount by designing the recesses to have a desired capacity to contain toner.
However, if the surface of the development roller is made of metal and has surface unevenness as in JP-2008-292594-A, it is possible that toner is charged excessively, degrading image developability, depending on environmental conditions or the type of toner. To adjust toner charging, the surface of the development roller may be coated with resin. Even if the surface is coated with resin, toner filming can still occur in development rollers having surface unevenness in regular arrangement.